Graham Rice's New Plants Blog

Editor-in-Chief of the RHS Encyclopedia of Perennials; writer for a wide range of newspapers and magazines including The Garden and The Plantsman; member of the RHS Herbaceous Plant Committee and Floral Trials Committee; author of many books on plants and gardens.

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As a cut flower, ageratum is does not always come to mind. We tend to think of it more as an edging plant. But it’s actually one of the best of all blue flowers for cutting, especially as it’s not difficult to grow. And this year sees the arrival of two new varieties, one available as seed and one as plugs.

‘Everest Blue’ (above left, click to enlarge), new from Holland, is perhaps a fraction taller, reaching
20-26in/50-65cm in height and continues to produce new colour all
through the summer.

‘High Tide Blue’ (above right, click to enlarge), new from across the Atlantic, is a very productive variety reaching 20-24in/50-60cm in height and is very well branched.

Frankly they both look good, and your choice may well depend on whether you’d rather grow plants from seed, in which case choose ‘High Tide Blue’, or if you’d prefer to start with mini-plugs, in which case choose ‘Everest Blue’.

Both are happy in any reasonably fertile soil, but prefer at least six hours of sunshine each day. Expect up to twenty cut stems from each plant, cut the stems when the central floret in the head is completely open and there is colour in the florets to the side. Always use flower preservative and that should give you a ten day vase life.

Cut Ageratum stems do not store well or travel well – so Ageratum ideal as a home grown cut flower

Most of us are familiar with the shrubby hibiscus, attractive summer flowering shrubs with single or double, mallow-like flowers. But there’s also a wide range of hardy perennial types that we hardly ever see – and they have HUGE flowers. Now’s your chance to try the latest varieties (above, click to enlarge).

Let’s start with the flowers. They’re like lavatera or single hollyhock flowers, in red, pinks, bicolours and white but they reach from 8-12in/20-30cm across. They’re probably about the size of your head! They develop on upright stems from large thongy roots and flower from mid summer into autumn on plants about 3ft/90cm high. Can you imagine?

So why do we see them so rarely? It’s not that they’re tender. A few years ago, when I was in Michigan, I visited a nursery where one of the top breeders was trialing new varieties. They were planted in a windswept field in an area where the winter temperature reaches as low as -29C/-20F. So they’re tough.

But they do like a hot summer, so they’re more likely to thrive in the warmer parts of the country and they appreciate a cosy sunny area in cooler regions. They’re also good in large containers.

Six varieties are available this year, from three of America’s top breeders, so you can choose the colours you prefer.

The recent trial of Alstroemeria at the RHS garden at Wisley not only highlighted the best of the familiar flowering types, but there were also some fine variegated forms that caught the eye, two of which received awards. Too new to be in the trial was this startling new variety from Australia, Alstroemeria Rock ‘n’ Roll (‘AlsDuno1’). (It’s sometimes written as Rock & Roll.)

Making a bushy plant eventually reaching about 30-40in/80-10cm height and 20-28in/50-70cm, the centre of each leaf is brightly splashed, the colour starts off yellow in the young leaves and then matures through cream to white. And because the pale variegation is at the centre of the leaf, where it’s at its thickest, rather than at the thin and vulnerable edge of the leaf it doesn’t scorch.

Topping this bright foliage display are clusters of six to twelve, 2-3in/4-7.5cm flowers in a contrasting vivid orange-scarlet. They start to open in late spring and continue into the autumn, especially if the faded flower stems are pulled right out at the root.

Happy in large containers, or in any fertile soil that is not parched or waterlogged, Alstroemeria Rock ‘n’ Roll is happy in sun or a little shade. To ensure that plants in beds and borders overwinter happily in chilly conditions, cover with a deep mulch of bark chips in autumn after the stems are cut down.

Cannas are very fashionable these days. With the recent enthusiasm for plantings with a tropical air, the bold foliage and colourful flowers of cannas create an exciting impact that’s seen far more often than a few years ago.

But there are two problems. One is that cannas are big plants; 5-6ft/1.5-1.8m is perfectly normal and with that hefty foliage they take up a lot of space. Also many of the familiar varieties are infected with virus and don’t always thrive the way we hope.

Dwarf cannas from seed solve both problems. Their scale is more suitable for small borders and small containers, and virus diseases are not transmitted by seed so they start off perfectly healthy.

Dwarf seed-raised varieties have been around for a while and, to be honest, they’ve not been a great success. But they’ve all had green leaves and it’s the purple- and bronze-leaved types which are the most popular.

Step forward Canna ‘Tropical Bronze Scarlet’. Reaching only 24-30in/60-75cm in height, with a spread of about 16-18in/41-46cm its foliage is deep coppery bronze and the flowers bright red with a slight carmine haze. At half the size of most other cannas it’s both small and dramatic. And you can keep the rhizomes till next year.

Sow this month, grow warm and harden off before planting out after the last frost.

Creating new magnolias is a long term project. New Zealand magnolia breeder Mark Jury made the cross that has now led to the appearance of this impressive new variety way back in 1996. And it looks as if the wait has been worthwhile.

Unlike most spring flowering magnolias, Fairy Magnolia® Blush (‘MicJur01’) is an evergreen variety, in the group that until recently was classified in a separate genus, Michelia. Plants eventually reach about 9ft/2.7m high and about 8ft/2.4m across, with neat, dark green, lustrous foliage. It makes an attractive plant even when not flowering.

From March to May, rich, honey-colored buds open to reveal blush pink fragrant flowers with attractive veining. And they open all along the branches, not just at the tips – that was one of the features that distinguished Michelia from the tip-flowering Magnolia.

Fairy Magnolia® Blush is happy in full sun or partial shade and in any moist but well-drained soil. It makes a fine small garden or container-grown specimen, or an attractive fragrant hedge. It can be trained to a trellis and would be happy on a west wall near a door where the prettily patterned flowers and their attractive fragrance can be appreciated. It even makes a colourful flowering standard.

Fairy Magnolia® Blush is the result of a cross between the white flowered Chinese Magnolia laevifolia (formerly Michelia yunnanensis) and the pink flowered Magnolia ‘Mixed Up Miss’, a hybrid between M. figo and M. doltsopa. Both parents are very fragrant, as is Fairy Magnolia® Blush.

Plants that combine good looks with good flavour at the table are especially valuable in small gardens and in containers so the arrival of this new chilli pepper, ‘Basket of Fire’, is very welcome.

So many chillies are either very upright or very dwarf and compact but although ‘Basket of Fire’ starts off as a rounded plant when young (as in the picture), it soon spreads out and develops a semi-trailing habit. Reaching about 12in/30cm in height it spreads out to twice that so ideal is in a container. And this new British-bred variety has two other important features.

The small fruits can be used at any stage from early in their maturity, when they’re deep purple, through yellow to orange to full red ripeness. And this blend of colours makes a very attractive plant. You get the best of both worlds. Are they hot? Well, its Scoville heat rating is about 80000shu which puts it in the middle range between Cayenne and Habanero chillies.

Plants are fairly quick to mature, there should be some useable fruits about five weeks after transplanting and fully ripe fruits after about three months. And ‘Basket of Fire’ is very prolific. Three plants can produce several hundred chillies and with useful tolerance to cool conditions the fruits continue ripening until well into the autumn. They can then be dried and stored for the winter.